Insulating compound and process of making the same.



G. F. DREHER.

INSULATING COMPOUND AND PROCESS OF MAKING THE SAME.

APPLIOATION FILED DEC. 29, 1908. RENEWED JAN. 12, 1911.

Patented June 17, 1913.

Fiql.

Witnesses: Inventor: 6M 9 Adm/4 v Gustav el fn ehe r:

$ y fl25 GUSTAVE .F.

rear men DREHER, OF 'SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

' INSULATING COMPOUND AND PROCESS OF MAKING THE SAME.

meteor. Application filed December T0 cll w i zlom 2'25 may concern.

Belt known that I,.GUs'rAvn F. DREHER,

a citizen of the United States, residing'at.

Schenectady, county of Schenectady,= State of New York, have invented certain new and useful Improvements in Insulating Compounds and Processes of Making the Same, of which the following is a specification.

This invention relates to a new insulating material for use in' electrical apparatus, and to the process of making-the same. The material finds a special field of service in dynamo electric machines, where it is employed to insulate from each other the segments of the commutators;

- mica "and various other msulating materials have been used for this purpose, but there are certain objections in practice to these substances, which I have endeavored to overcome by my invention. It is highly desirable tohave an insulating material which will-wearoif equally with the copper segments, so that no projecting ridges will be left to cause chattering and sparking at the brushes. My improved compound is found in practice to wear down smoothly so that the surface of'the commutator remains-in good condition and requires no dressing ofi even after long service.

In the accompanyingdrawing, Figure 1 represents a pieceof'my improved insulating compound ready for insertion into a commutator, andFig. 2 shows a portion of-a coinm'utator in which the segments are separated by sheets of my material. I

In proceeding to make the insulating materiali-hereinbefore referred to, I prepare a powder composed of certain proportions of dry kaolin, or kaolin and lime, and lime,

glass, green silko and red silko. The preferred proportions are 237 parts of dry kaolin, 37 parts of finely powdered glass,' 88 parts ofgreen silko (powdered slate) and 2 parts of red silko. These ingredients are reduced to a fine powder and thoroughly mixed together. I then add a certain quantity of asbestos staple, preferably in the proportion of 30 parts of staple" to every 70 arts of. the mixture; making 156 parts of asbestos for the above-named quantity of the mixture. This compound 1s -run through what is known to asbestos manufacturers as the wet machine, from which it emerges in the form of sheets. To these sheets is then applied silicate of soda," preferably by Specification of Letters Patent.

Heretofore' Patented Julieta, iaia.

29, 1968, Serial No. 469,767. Renewed January 12, 1911. Serial No. 602,278.

this substance at a specific gravity of 35 degrees Baum. After saturation, the sheets are removed from the tank and dried ,in the open air. When dry they can be reduced to the proper thickness, preferably by milling or grinding with sand cylinders. I

v then place these sheets between flat iron plates and clamp them together in piles, so that a quantity can be subjected at the same time to pressure, preferably in a hydaulic pgess, and varying from 7 50 to 1000 pounds to the square inch. This insures the sheets being true planes. The flat iron plates are then secured in clamped relation upon the sheets by bolts and upon removal from the press, the clamped sheets are introduced into gas-heated.furnaces and fired at a high'temperature, preferably about 450 degrees centig'rade, more or less.

The sheets produced by this process are stiff, and they are capable of resisting a heavy pressure, bled with the segments of a commutator and the whole compressed into shape without so that they can be assemthe commutatoris'kept in a smooth and satisfactory condition for a long time. The dielectric qualities'of the compound have been found to be excellent.

Fig. 1 of the drawing shows a sheet l of my irnproved insulating compound, and Fig. 2 shows a portion of a commutator consisting of segments 2 separated by thin sheets 1 of the insulating material. But in addition to its use in commutators, this material is applicable in many other places Where the conditions are such as to call .for an insulating substance having rigidity and the capacity to resist high temperatures and high voltages. I

I'do not desire to restrict myself to the particular-ingredients or the particular proportions mentioned herein, since it is apparent that they may be changed and modified without departing from my invention.

What I claim as new, and desire to secure refractory earth in powdered state, asbestos and silicate of soda compressed and fired under pressure at high temperature.

2. An insulating compound composed of Y of soda compressed and fired under pressure,

refractory earth, lime, asbestos and silicate powdered glass, 17 per cent. of powdered slate and 30 per cent. of asbestos staple, soaked in silicate of soda, compressed and fired.

dry kaolin, powdered glass, powdered slate (silko) and asbestos staple, forming into 5. The process of making an insulating 1 material which consists in mixing together sheets, soaking in silicate of soda, compressing, and firing.

6'. The process of making an msul'atmg material, Which consists in mixing together dry kaolin, powdered glass,'silk0, and asbestos staple, forming the compound into sheets, treating said sheets With silicate of soda, drying, subjecting said sheets to a pressure of several'hundred pounds to the square inch, and then firing them at high temperature.

In Witness whereof, I have hereunto set my hand this 28th day of December, 1908.

y GUSTAVE F. DREHER.

Witnesses: HELEN ORFORD,

BENJAMIN B. HULL. 

